1. Field of the Invention
The invention is related to the field of magnetic disk drive systems and, in particular, to fabricating wrap around shields of a write head.
2. Statement of the Problem
Magnetic disk drive systems typically include a magnetic disk, a recording head having write and read elements, a suspension arm, and an actuator arm. As the magnetic disk is rotated, air adjacent to the disk surface moves with the disk. This allows the recording head (also referred to as a slider) to fly on an extremely thin cushion of air, generally referred to as an air bearing. When the recording head flies on the air bearing, the actuator arm swings the suspension arm to place the recording head over selected circular tracks on the rotating magnetic disk where signal fields are written to and read by the write and read elements, respectively. The write and read elements are connected to processing circuitry that operates according to a computer program to implement write and read functions.
Write heads and other components of the recording heads are typically produced using thin-film deposition and patterning techniques. The several material layers which make up a write head for a magnetic recording head are typically formed by depositing full film materials of the write pole layers on a wafer substrate, depositing and patterning a masking layer over the write pole layers to form a mask structure, etching the exposed portion of the write pole layers around the mask structure, and then removing the mask structure. A trailing shield or wrap around shield may then be formed around the write pole using a similar process. A wrap around shield comprises a trailing shield along a trailing surface of the write pole, and side shields disposed on sides (i.e., along surfaces of the write pole adjacent to neighboring tracks) of the write pole. Shields are formed to prevent the write pole from writing to neighboring tracks or bits during a writing process.
Prior art write head fabrication processes encounter problems in precisely aligning the layers of the write head with each other and with respect to the center of the write head. Further, problems are encountered in accurately controlling the dimensions of the write pole and write head. These dimensions include the track width of the write pole, the flare point, the flare length and the throat height of the write head. For example, the dimensions of the write pole and the location of the flare point of the write pole are typically fabricated at the same time using a photolithographic process. Defining both the track width and the flare point of the write pole at the same time results in an alignment of the flare point and the track width with respect to other structures of the write head which is not as accurate as desired. Further, another photolithographic process is used to define the trailing or wrap around shield, which leads to additional alignment problems because of limitations in the accuracy of the photolithographic process. Because of these alignment issues, the various structures of the write head may not be accurately aligned, which may lead to recording problems of the write head.